Bicycle Generator with Offset Rotor and Gearbox
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Solution Overview
Problem
Existing electric power generation units for bicycles are not compact enough and do not achieve high-power density, which limits their efficiency and usability in chainless bicycle designs.
Innovation Solution
The proposed electric power generation unit features a pedal shaft with an electric generator having a rotor with a parallel offset to the pedal shaft, coupled with a gearbox to transmit torque efficiently. This design allows for a compact and lightweight structure with high-power density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the electric generator is arranged coaxially to the pedal shaft, then the structure is simpler, but the unit becomes larger and less compact
Solution Approach 1:
The patent transitions from a coaxial arrangement (one-dimensional alignment) to a parallel offset arrangement, utilizing a second spatial dimension to position the generator relative to the pedal shaft. This dimensional change enables more efficient space utilization and achieves compactness without excessive structural complexity.
2Reliability
If a chain connection is used between pedal shaft and powered wheel, then power transmission is reliable, but the bicycle becomes less compact and more complex
Solution Approach 1:
The patent merges the electric generator with the drivetrain components (pedal shaft, gearbox, powered wheel) into an integrated assembly. The generator is mounted directly on the drivetrain structure, eliminating the need for separate chain connections and external motor mounts, thereby reducing overall complexity while maintaining reliable power transmission.
3Power
If the generator is mounted with parallel offset to achieve compactness, then power density increases, but torque transmission becomes more complex
Solution Approach 1:
The patent introduces a gearbox as an intermediary component between the pedal shaft and the generator. This intermediary mechanism efficiently transmits and transforms torque from the parallel offset pedal shaft to the generator, enabling compact mounting while managing the complexity of torque transmission through a well-established mechanical component.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The compact and lightweight design of the electric power generation unit achieves high-power density, enhancing efficiency and usability in chainless bicycle applications, while providing a natural pedaling feel.
Implementation Method 1
an electric generator with a rotor and a stator, wherein the axis of rotation of the rotor is arranged with a parallel offset to the pedal shaft
Implementation Method 2
a gearbox configured to transmit torque from the pedal shaft to the rotor of the electric generator
Data Source
AI summary
An electric power generation unit for a bicycle comprises a pedal shaft with pedals and an electric generator with a rotor and a stator, wherein the axis of rotation of the rotor is arranged with a parallel offset to the pedal shaft. The electric power generation unit further comprises a gearbox configured to transmit torque from the pedal shaft to the rotor of the electric generator. The electric power generation unit further comprises a housing comprising at least the electric generator and the gearbox, and/or the axis of rotation of the rotor is arranged with a parallel offset to a powered wheel of the bicycle.